Automatic testing system to test automatic switches



Feb. 16 1926. 1,573,413

H. w. MHCDOUGALL AUTOMATIC TESTING SYSTEM TO TEST AUTOMATIC SWITCHES Filed 1925 Feb. 16,1926. 1,573,413

H. W. M DOUGALL AUTOMATIC TESTING SYSTEM TO TEST AUTOMATIC SWITCHE3 Filed Nov. 19, 1923 9 Sheets-Sheet 2 70 if ESTED Feb. 16,1926. 1,573,413

H. W. M DOUGALL AUTOMATIC TESTING SYSTEM TO TEST AUTOMATIC SWITCHES Filed Nov. 19, 1923 9 Sheets-Sheet 5 I calm/Ecru? Feb. 16 1926. 1,573,413

. H. w. M DOUGALL AUTOMATIC TESTING SYSTEM TO TEST AUTOMATIC SWITCHES Fil V. 9 9 tS-Shfit 4 Af/M Feb. 16,1926. 1,513,413

' H. W. M DOTJGA-LL.

AUTOMATIC TESTING SYSTEM TO TEST AUTOMATIC SWITCHES Filed Nov. 19, 1923 9 Sheets-Sheet 5 Feb. 16 1926. 1,573,413

- H. w. M DOUGALL AUTOMATIC TESTING SYSTEM TO TEST AUTOMATIC SWITCHES Filed Nov. 19, 1923 9 Sheets-Sheet 6 //1 van/0n" flak/y W Mac Dagya/l.

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kil /3 Feb. 16 1926. 1,573,413

H. w. M DOUGALL AUTOMATIC TESTING SYSTEM TO TEST AUTOMATIC SWITCHES Filed Nov. 19, 1923 9 Sheets-Sheet 7 Feb. 16, 1926. 1,573,413

r H w. M DOUGALL AUTOMATIC TESTING SYSTEM T 0 TEST AUTOMATIC SWITCHES Filed Nov, 19, 1923 9 Sheets-Sheet a Feb. 16 1926. 1,573,413

H. w; MHCDOUGALL AUTOMATIC TESTING SYSTEM TO TESTAUTOMATIC SWITCHES Filed Nov. 19, 1923 9 Sheets-Sheet 9 Patented Feb. 16, 1926.

UNITED STATES PATENT OFFICE.

HARRY W. MAQDOUGALL, OFEAST ORANGE, NEW" JERSEY, ASSIGNOR TO WESTERN ELECTRIC COIKPANY, NEW YORK.

INCDEPORATEID, OF NEW YU BK N. Y.,A COBBORA'I'EON OE AUTOMATIC TESTING SYSTEM TO TEST AUTOMATIC SVJITCI-IES.

Application filed November 19, 1923. Serial No. 675,525."

To all 'ZUIIOIIL it may concern:

Be it known that I, HARRY MAC- DOUGALL, a citizen of the United States, re siding at East Orange, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Automatic Testing Systems to Test Automatic Switches, of which the following is a full, clear, concise, and exact description.

This invention relates to a telephone exchange system, and more particularly to a testing s tem for use ina machine'switching system for testing selector switch units.

It is an object of thisinvei'ition to provide an improved testing system.

The switching units of an automatically operated telephone exchange are made up of control apparatus, relays and auxiliary circuits to control their automatic progression, and further control other switching units and the line apparatus. A large number 01 such switchingunits are required in a system of this kind, any of which may be arbitrarily selected when idle to complete a service connection. Thus, it is apparent that a switchingunit giving ineiiicient service is not immediately noticed; Since the apparatus of a switching unit requires adjust ment within limited variation, it is important that these unitshe regularly tested to determine their ability to render eliicicut service. In order'to reduce the cost of such maint ice, it is desirable to use an auto maticaliy progressive testing system requir ing a limited amount of manual operation. .Vith this type oftesting system, the'routine test of the automatic selector switching units of an exchange may he very rapidly accomplished.

A feature of this invention relates to the use of common automatically progressive controlling equi nncnt in combination with automatically progressive testing equipment to successively select switches to he tested and to variably direct the selected switches to progressively changing testing equipment.

A further feature oi this invention is in the provision of an automatically progresautomatic switches-to he tested.

Other features of this invention relate to means to manually direct the testing control device for a plurality of tests of particular. automatic switches, means to arrest the progression ot the testing system during any one ot a plurality of tests of a. switch, when an unstandard condition is encountered, means to repeat a plurality oi tests 01 a switch or to repeat any one of said plurality ottests of a switch, and means to opcrate a compound timing device to limit the time for selecting a switch to be tested, and to limit the time for each of a plurality of tests of an automatic switch.

These and other features of the invention will'be apparent from the following description taken in connection with the accompa-nying drawing.

l Jhile the invention has been disclosed as particularly adapted for testing switches of the panel type, it will be apparent, however, from the following description, that the invention has a wider utility and that by slight modification it could be adapted for testing' other types of selector switches.

Fig. 1 shows keys to start an automatic routine test. of final selector swit-hcs and keys to control special tests of particular iii Al selector switches.

Fig. 2 illustrates register switches 50 and connected to terminal strips. A cross connection is shown between the terminal strips and the contacts o1 the register arcs to illustrate a typical arrangement for an automatic routine test of final selector switches in a machine switching ofiice. The regiter bru hes 52 and 72 and their associated contacts are wired to control the mov ment of the register switches under control of the keys. The remaining register brushes and associated contacts are wired and cross connected in a manner to control the movement of the testing chntrol circuit so that all final selector switches of the ollice he tested.

Fig. 3 illustrates connectors 200 and 300. These connectors are of the sequence switch type and are controlled in such manner that particular selector switches are removed from service and associated with the testing control circuit.

Fig. 4 illustrates apparatus and, circuits to control the positioning otf the test selector.

Fig. 5 illustrates a plurality of testing devices operated in combination with Fig. 6.

[The position the sequenceswitch "5 controlsthe'particular testing combinatesting control circuitindependent ot' the incoming selector sequence switch.

Fig. 8 shows a' final selector switch and its auifiliary circuits. This is a typical final selector switch of the type-to be tested by this testing system.

Fig. 9 illustrates a compound timing device operated in such. a manner that switch 970 is progressively positioned to count a predetermined time period. for the operation of the testing control circuit. Switch 970 is progressively positioned during the progressive movement of the testing..control circuit and until a final selector switch to be tested. is seized. Timing switch v9% is operated to time the period during which the finalselector is under test.

The time'pe'riod allotted for the operation of switches 970 or 980 is adjusted .in such manner thatshouldthe various operations not be completed within a predetermined time an alarm is sounded to indicate, such 1 condition to an attendant.

Fig. 10 1s a diagram showing the V which the sheets of drawings should be arranged.

'Figs11 illustrates a tabulated diagramshowing the location of thetinal selector.

switches on the panels andthe necessary steps to test such linal selector switches.

The cross connection of the terminals illustrated in Fig. 2 is made in accordance with this diagram.

Description of apparatus.

. .IKeys ,16and 17, shown in Fig.1, are the start keysto initiate an automatic routine test of the final selector switches of an otlice.

Key 15 is for restoring the testing control circuit to normal. 7 register switches 50 and for a particular Keys -1 to 13 control test. Keys 18 to 21 and 25 to 28 further order in control the action of the testing control circuit during the test of particular automatlc switches. Key 14 establishes miscellaneous circuits for particular testing control. Keys 1 to1 3 18 to'21, and to 28, are mechanically locked and electrically released.

Keys 14.110 17, inclusive, are the ordinary type of'locking key whicharemanually released. Key 29 is a non-lockingfkey used 7 to advance the register switches 50 and 70 .to make a neW cycle of routine tests of the final selector switches.

Register switches 50 and 70, shown in Fig. 2, the selectorcontrol' switch 149 shown in Fig. 5, and theswitches 970 and 980 of thetiming device shown in Fig. 9 areofa well known step-by step type. The switches shown in Figs. 3, 1, 5 and 6 are of the well known sequence switch type I Ihe 'incoming'selector switch shown in ,FigJT and the tinal' selector switchshownin Fig. 8 are of the,same"character as -the one shown and describedin detail in Patent .No. 1,123,696, issued January 5, 1915, to Edward B. "Craft and John N. Reynolds;

More specifically these selector switchesand their auxiliarycircuits are describedin de- 7 tail in Patent No. 1,395,977, issued Novena berf 1, 1921, toliranklin A- Stearn and lfrederick J. "icudder. v

General description.

register brush 53 controls the'brush selec-.

tie-11 oi the; test selector, switch (Fig. 7);

Register brush controls the group selection of the testv selector switch. Register brush 55 controls thenumber of finalselector switches tested during the time, use,

register switch 50' is resting in' position'l.

Register brush 56 controls the testing of the test selector to ascertain whether it is characterized as busy or idle. Register brush 5'? controls the movement of the connector switch and thus controls the selection ot the test selector switch, to be used during the test ot certain final selector switches.

, lVith register switch 50 in position 1 connector 200 is rotated from its normal position 1 to position 2, thus associating the test selector switch shown in Fig. 7 "with the testingcontrol circuit. The test selector switch is. then automatically tested by the testing control circuitto ascertain whether it is busy or idle. If it is idle,- it is autoinatically removed from regular service. Upon seizure of the test selector switch, a relay is released in the testing control circuit to rotate the sequence switch shown in in such manner as to further control connector 200. The connector is thus rotated to position and, in thus rotating, es-

tablishes crcuits to control further movement of the testing control circuit.

When the sequence switch (Fig. 4) has rotated to position 3, a circuit is established under the control of register brush to position the selector control switch 44 9. The positioning of the selector control switch is for the purpose of preestabli.shing the number of final selector switches to be automatically and progressively tested during the time that register switch 50 is resting in position 1. r

The terminals 7 35, 7 86 and 737 represent one set of terminals mounted in a horizontal row on the final selector switch frame. There are a large number of like sets of terminals on this frame divided into what are known as panels. The panel of terminals is divided vertically into banks and the hanks of terminals are divided vertically into groups. In one type of telephone system, the panel is sub-divided into five banks and the bank is divided into four groups. Above each group is a set of terminals known as overflow terminals. The purpose of' the overflow terminals under ordinary service conditions, is to arrest the upward movement of the selector switch elevator that has hunted over a complete group of terminals and found them busy.

The testing control circuit is designed to direct the test selector to the first terminal of a particular group ofterminals that are connected to final selector switches. .Vhen the test of said first final selector switch is completed, the test selector is advanced to the second final selector switch,

stepping forward one set of terminals ungroup above the group that has been tested. Each time that an overflow terminal is encountered, switch 449 steps two terminals. Therefore, if selector control switch 449 is initially arrested in its forward movement in position ,1, four groups of final selector switches are tested before switch 449 is again returned to normal. Upon the restoration of switch 449, the test selector is repermanently busy.

stored to normal and register switch 50 is advanced one position to again direct. the test selector to a second series of final selector switches to he tested. Selector control switch i ls-is again positioned to control the number of groups of final selector switches tested during the period of time that the register switch 50 is resting in position- 2.

l /hon a final selector switch is chosen for test, the testing control circuit first ascortains whether it is busyor idle. If it is busy, the testing control circuit will remain thus connected until it becomes idle. The final selector switch may be connected in service, if so a connection of the testing control device to the final selector switch does not interfere with the service connection. Special provision is also made in the testing control circuit to automatically pass busy final selector switches. A lrey is oper ated to add this feature to the automatically pYOQQIGSSlVG test. A key is also provided to be operated and released to step the testing control circuit off of a final selector switch if the final selector switch is idle, the apparatus shown in Figs. 5 and (i' is actuated to direct the final selector switch to test lines.

There are three test lines provided to which the final selector is directed for test. The first and second test lines are made permanently busy. The third test line is connected to the apparatus shown in Figs. 5 and 6, and the condition associated with the third test line is varied in accordance with the desired test of the final selector switch. The sequence switch shown in Fig. 5 is progressively positioned to vary the condition associated with the third test line. A plurality of tests are madcupon each final selector switch and its auxiliary circuits. The automatic p "session of these tests is in the following order:

1. Direct line M70.

2. Direct line busy.

Upon the completion of test No 1, the final selector switch is restored to normal and the sequence switch (Fig. 5) is rotated to position 3 to change the condition as sociat-ed with the third test line. The fin al selector switch is again directed to the third test line where a busy direct line is now 'sin'iulated thy the apparatus shown in Figs. 5 'an'd 6. The'tinal selector switch responds to this condition bywattein'pting to senda.

busy t-one and busy flash to thecalling subscriber or to .an operator. This [flash is transmitted over conductor 851 to testing apparatus shown in Figs. 5 and 6. Uponthe rece pt of a predetermined number oi such fiashes, the final selector switch 1s again-re stored.

P. B. X. Line idle mat of 'group).

oftest No.2, the in F g. 5 as adwired in such manner thatthe final .sclector will not ihunt further. Shouldthis last line be-"a busy line thefinalselectorswitch will return'iabusy tone and busy flash, the same as it would it" connected to a directline busy. In"this test, the final selector switch is "directed to the-third test-line to which a condition is now connected representing -a privatebranchexchange line that is idle.

4. LaSt-'P.B. X. Zine idle.

Upon the completion of test No. 3, the finalselector is returned toin'ormal and'again directively positioned by the testing; circuit, also thesequence;switch'shown in-F 5 is rotated from position 5 to position r. In this test, it is directed to thefirst test line fromwhich it hunts over the sccondtes't line and is arrested upon the third testline'. As previously described, thefirstand second test lines are permanently wired to represent busy Pill. X. lines to test the hunting ability ofthe final selector switch. In-this test the third test lineis associated with apparatus in Fi 5 to represent an, idle P. B.

X. line, the last one of a group.

' Busy .P. B. X. last of grown).

Upon completion of test No. 4, the final selector switch is'restored to normal and again directed to test lineNo. 1. Also the sequence switch, shown in Fig. 5, is rotated from position 7 to position 9. The final selector switch now hunts over test lines "Nos. 1 and 2 and isarrested when connected to test lineNo. 8. -In this test, the apparatus associatedwith test line No, 3 represents a busy'last line of a P.--B. group -The hn'al selector :sequence switchnow rotates *to'a position'wherethebusy flash and interruptedyground. are connected-to the tip final select-or switch is restored 110;!101111txl.

and again directed to testline No. -1, also the sequence switch shown in'Fig. 5'is rotated from position 9 to position 11. T he; final selector switch now hunts over test lines 1 and 2 and is arrested when connectedto-test line- N0. 3. In this test,-apparat us is associatedwithtest line-No. 3 to represent one of the'intermediate private branch exchange .lines in a group of such lines. 7 '7. [V0 test.

-Upon the completion of testNo. 6, thefinal selector switch is restored to normal and thersequence -switch,-Fig. 5, is rotater "-to position=13. This test is made to simulate a service trafiic condition brought about by -a line maintained husy'for a considerable period. The line is reported to a, special operatorwho initiates a no test call to direct a final selector switch to the aforesaid busy pline I to- .imestigate-this' condition.

. -'Ihe final.selector switch is directed to the thirdtest l-ine. v In thistesta special means v is'used to control the final selector switch. .The-condition associated with test line No. 3-represents a' direct line busy. The special means of control causesthe final selector" switch to be connected .to theibusy line instead ot returning a busy tone andflash.

8. Time measure release.

Upon the completion of test No. 7, the final selector switch 1s restored to, normal and the sequenceswitch, Fig. 5, is advanced toposition 15. "Thepurpose ofthisQtest v isto determine the condition of the release apparatus when the final selector switch is connected toa-called-linc with the receiver oil" the switchh'o'ok.

Up'onfthe completion of test No. 8, the final selector switch is restored to, normal and the sequence switch, Fig. 5, is advanced to apo-sitionto controlthe advance of the Conductors 221 .to 231 inclusive are con-' gILGGtQCl to one test selector;,conductors 232 to 2 12, inclusive, areconnected to a second "test selector; conductors 243 to 253, inclusive, are connected'to a third test selector, etc. Two connector switches are shown,

there may, however, be any number of like connector switches used to associate a large plurality of test selectors with the test control circuit.

The testing control device may be manually controlled from a group of keys shown in Fig. 1. to directively position a particular test selector upon terminals connected to a particular group of final selector switches. Register switch 50 or may be selectively chosen for rotation to a particular position. Also, either connector 200 or connector 300 may be selectively chosen for rotationto a particular test selector. The register switch and the connector switch not chosen remain in their normal positions of actuation. One of keys 1% to 21 directs the test selector to any one of four groups of final selector switches. The number of groups tested is regulated by the operation of one of keys 25 to 28.

The timing circuit shown in Fig. 9 is actuated when start keys 16 and 17 are operated, either to make an automatically progressive routine test or to make aparticular test. A predetermined time interval is allowed for the testing control circuit to ad vance in a progressive manner to seize a test selector and direct it to the final'selector switch to be tested and seize said final selector switch. When this is accomplished, a second timing device is started into operation to count a predetermined time interval of sufficient duration to allow a plurality of progressive tests of the final selector switch and its auxiliary circuits. Upon the operation of the second timing device, the first timing device is restored to normal and upon the completion of the test of the final selector switch the second timing device is restored to normal. During the time that the test selectoris being advanced to the next final selector switchto be tested the first timing device is again operated. In this manner all operations of the testing system are covered by a timing device that Will sound an alarm at any time that an operation is not completed within a predetermii'ied time interval. a

When an unstandard condition has been encountered by the testing device the automatic progression is arrested and the alarm is sounded to attract the attention of the maintenance man to the circuit in trouble.

The maintenance man records the unstandard condition and ascertains its origin'if possible. The testing device is arranged so that the test may be repeated any number of times if the final selector switch is found in an unstandard condition. l/Vhen an unstandard condition is encountered that connot-be easily remedied, a record of the unstandard condition ismade bythe maintenance man and the'testing circuit anditesti gcoatrel circuit are manip l t d y-lwy 630, shown in Fig. 6, to advance to the next final selector switch in the sequence of test.

Having now described in a general way the apparatus employed in conducting tests and the method in which it is to be used, it is thought that the invention will be better understood by the consideration of the specific manner in which it functions.

Detail description.

Let it be assumed that an automatic routine test is to be made of the final selector switches of an ofiice. Start keys 16 and 17 shown in Fig. 1 are actuated. These keys remain locked throughout the automatically progressive routine test of the final selectors. Various circuits are established by the operation of the start keys that are not efi'ective at this time, and will be described upon the actuation of apparatus over circuit paths through the key contacts.

The actuation of start key 17 establishes a circuit to operate start relay 425. This cir-- cuit may be traced from grounded battery, through the winding of relay 425, right lower and left upper contacts of sequence switch spring 320, upper contacts of sequence switch spring 220, to ground through the right outer contacts of key 17. Relay 425 in attracting its left armature establishes a circuit to actuate magnet 51 of register 50. This circuit may be traced from grounded battery, through the winding and contacts of register magnet 51, left outer contact and armature of relay 41, brush 52 and its associated normal contact, left and right nor mal contacts of key 18, left inner normal contacts of key 29, to ground through the left contact and armature of start relay 425. The actuation of register magnet 51 rotates register 50 from its normal position to position 1. The operation of start relay 425 further establishes a circuit through the winding of relay 42. This circuit may be traced from grounded battery, through the winding and contacts of register magnet 51, left outer normal contact and armature of relay 41, winding of relay 42, contact of sequence switch spring 405 to ground. through the left contact and armanre of relay 425. Relay 42 is prevented from operating until register switch 50 has rotated from its normal position to position 1, by a ground shunt previously traced to actuate register magnet 51. Upon the positioning of register 50 in position 1, this ground shunt is'removed to cause the operation of relay 42. Relay 42 is sufficiently high in resistance to prevent register magnet 51 from again operating.

The circuit established through the right inner contact and armature of relay 42 is not effective at this time. An obvious circuit established through the right'o'uter contact and armature of relay 42 to operate relay 43.

The operation of relay 4:3 establishes locking clrcult for itself which may be traced from grounded battery, through its winding, left contact and arn'iature to groundthrough the right inner contacts ofkey 16. The operation of relay 43 further establishes a circuit to operate relay 39, This circuit may be traced fromgrounded battery, through the winding of relay 39,

to ground throughthe left outer contact and armature of relay 43.. The circuits established by the operation otrelay 39 arenot effective at this time.

The rotation ofregister switch 50 from its normal position to position 1 establishes various circuits taken in order as follows-1+ The positioning of register brush 57 es tabli'sh'es' a circuit to rotate connector 200 selector of Fig.

from position 1 to position 2'. Tlris ci rcuitbattery,

may be traced from grrunderl through the winding 01 sequence switch magnet 201, right" lower cont-act of sequence switch spring. 215, lower'contacts of sequence switclr'spring 319, tern'rinal strip-67, cross connection 86, terminalstrip (36,.br-ush 57, and its associated contact, left outer contacts of "key 17, right normal contacts of key 29,

left inncrarmature and contact of relay- 39 to ground througlrth'e lel t 111'11615 normal contacts of relay 40 Connector 2-00 now inposition 2' associates the testing control circuit with the test selector shown in Fig. 7. This association is throughconductors 221 to 231 respectively otconnectorQOOand conductors 721 to 731' respectively ofthe test The circuits established circuit established to ascertain the condition of the test selector may be traced from grounded battery, through the right inner armature and contact of relay 42, register brush. 56, and its associated contact, terminal strip 6i,'terminal strip 65, lower contact of sequence switch spring213,.right up per contact otsequence switch spring 407, left winding ott'relay 4:32 to ground, operating relay 4532. The operation-of relay establishes a circuit to rotate the sequence switclishown in Fig? This-circuit may bei'traecd from grounded battery, through the winding oft'sequen'ce switch magnet d0 0, right. upper contact of spring lUl 1e sequence;- switch".

relay 432, to ground throughthe left inner The sequence switch shown-in Fig. 4 nowrotates from position 1. to position 2, where a double test of the contacts of key 16.

condition of the test selector is made. 7 The testselector may be busy in service. This is characterized by a ground'connected to. conductor 721, by an associated'switch orthe auxiliary circuits shown in Fig. 7. 'The test selector may be idle, characterized by the.

absence of ground at conductor 721. It, however, may not have restoredtlie switch elevator, to its normal position. A test for bothof the" above conditions is made simultaneously. I v

The circuit totest the position of the selectcr switclr elevator may be traced from grounded battery, through the left inner armatureand contact of relay -12, registerbrush 5 6 and its associated contact, ter minal strips Ed and lower contact of sequence switch springfl'lti, winding of relay 4:33, conductor-361, lowe-rrontact of sequence switch spring 211, conductor 228, conductor 728, commutator segment 708, brush 709, to ground through lower contact of sequence switch spring 740. It is apparent that it theselector switch elevator-is'no-t in its normal position, brush 709 is notengagedwvith commutator segment 708, and tlius a circuit is not establishedto operate-relay;433, and the operating circuit it'onrelay 432 is thus This circuit may be traced'fromground through n'iaintainedrthrougli its left winding.

the. leftwinding of relay432, contact and armature ot'relay 433, left upper contact of se uence switch sarin 4-07 and thence to grounded battery connected to the armature oil relay 42 as previously trace-d.

The test selectorma-y be characterized as busy from aservice connection preceding the movement of the elevator switch from;

its uorn'ial'positionp The circuitfor testing this condition may be traced from grounded battery, through the right inner contact and armature of relay 4:2, register brush'56' and its associated contact,terniinal strip 64, ter

minal strip 65, lower contact of sequence sw tch sprmg 21:53, left upper contact of SQ quence switch spring 407, right winding,

204, conductor 221, conductor721, to a" ground characterizing the test selector as busy. Relay 432 is now maintainedin: an"

operated position until thetcst selector, Fig. 7, becomes idle. During the period of time that relay 4:32 is maintained' in an o aeratedposition, a circuit is established to lightlamp 442 toindicate that the'testing control} circu it'is associated with a busy test selector TlIlS" circuit may be traced l'roi-n groundsd.

batte y, through resis and. renters 0t re lay 4132,. o

contact and armature of relay 4S2, conductor 368, lower contact'o't sequence switch spring ground through the left inner contacts of key 16.

Assuming that the test selector, Fig. '7, is idle and that its elevator is resting in its normal position, relay is operated. Also, since ground is not connected to conductor 721, there i no circuit to maintain relay 432 in an operated position and it therefore releases.

The release oi? relay 4232 establishes a circuit to rotate the sequence switch, Fig.4, to position 3. This circuit maybe traced from grounded battery, through the winding of sequence switch magnet 4-00, left upper contact of sequence switch spring 401, left normal contact and armature of relay 432, to ground through the left inner contacts of: key 16.

In sequence switch position 3, a circuit is established to actuate switch magnet 450 to rotate the test selector control switch 449. This circuit may be traced trom grounded battery, through resistance 457, winding and contacts of switch magnet 450, lOTlit outer contacts of key 16, to ground through the left upper-contact of sequence switch spring 410. The test selector control switch 449 is now rotated under the control of its sel intei'rupting contact. The method used to arrest the rotation of switch 449, is to shunt the current flow through magnet winding 450 thus reducing the current flow to a nonopcrate Value with relation to magnet 450. This circuit may be traced from ground through the left inner contacts of key 14, register brush 55, and its associate contact in position 1, terminal strip 62, terminal strip 63, conductor 462, brush 451, and its associate contact in position 1, right upper and left lower contacts of sequence switch 423, resistance to grounded battery. The test selector control switch 449 is thus arrested in position 1. Test selector control switch 449. is positioned as described to count the number-of subgroups tested in a test group. t is variously positioned according to the number of subgroups to be tested in the test group selected by the position of register switch 50. The progression of switch will be hereinafter described.

A further circuit is established in position 3 of the sequence switch 4 to operate relay 428. This circuitmay be traced from grounded battery, through the winding of relay 428. to ground through the left lower contact oi sequence switch spring408. The operation of relay establishes an obyious circuit through itsflett contact and armature to operate relay 426. A circuit is also established to rotate the sequence switch "from position 3 to position 4. This circuit may be traced from grounded battery, through the winding of magnet 400, right outer armature and contact of relay 428 left upper contact or seq ence s itch spring 404, to ground through the normal contact and armature of the 0 counting relay 461.

In positions 3 and 4 of the sequence switch Fig. 4, a circuit is established to rotate connector 200 from position 2 to position 3. This circuit may be traced from grounded battery, through the winding of magnet 201, lower contact ofsequ'ence switch spring 216, to ground through. the upper contact of sequence switch spring 406.

It will be noted that upon the seizure oi? the test selector, a busy ground is connected from the test control circuit to conductor T21 of Fig. 7. This circuit may be traced "from ground through the left lower contact o't sequence switch spring 409, right normal contact and armature of relay 4232, upon its release as previously described. conductor 36S, lower contact of sequence switch spring 204, conductor 221 and conductor 721 of Fig. 7. This ground characterizes the test selector switch as busy so that it will not be seized for service connections. Upon the movement of connector 200 from position 2 to position 8, the busy ground traced through the contact and arn'uiture of relay 432 is replaced by a ground that may be traced through the contact and armature oi relay 202, right upper contact of sequence switch spring 203, conductor 221 and conductor 721 of Fig. 7. The purpose of connecting the busy ground from relay 202 of connector 200 is to maintain the test selector Fig. 7 busy to service switches during the period of time it is associated with the testing control circuit. The sequence switch. Fig. 4, will make a plurality oi? rewilutions during this time.

It willbe remembered that relay 426 held in an operated position from ground through the contact of relay 428. The operation of relay 426 establishes a circuit to operate relay 427. This circuit may be traced from grounded battery, through the Winding'of relay .427, left contact and arma ture of relay 426, brush 458 and its associated contact in position 1, to ground through the right armature and contact of relay 434. Relay 427 in opeeting. estab lishes a locking circuit for itself which is efi'ective in positions 6 and 7 of the sequence switch. It will be noted that the actuating circuit for relay 427 is opened when. the sequence switch rotates out or" position (3. This locking circuit may be traced from grounded battery. through its winding. right armature and Contact. le'l't outer normal contact and armature of relay 4%, to ground through the right upper switch spring 408.

It will: remembered that the sequei'ice switch Fig. 4. is now in position 4. In this position, circuit paths are established to directively control the test select-or for brush contact of sequence in the panel has been selected for test.

- snitch tram; pesitiaar ta: pantie s;

selection'in accordance with the positionwof register A circuituis accordingly establlshed to energize the updrive magnet (02. This circuit maybe traced from grounded 2 battery, throughthe windingof magnet 702,

conductor? 25, conductor 225, ,lower contact of sequence switch spring 208, conductor 364, upper contact Ofsequence switch spring.

412, right outei; armatureand contact ofrelay 428-, left upper contact of sequence. switch spring 404. to ground through the contact and armature oftheO countmgrelay 46.1. Simultaneous with the establishment ofthe above traced circuit, a fundamental circuit is established to, operate 1 conductor 222, lowercontact of sequence switch spring 205, conductor 367, uppercontacts of sequence switch spring 418-, register brush 53, and its associated contactin-position' 1, terminalstrip 58, terminal strip59,

conductor 30, conductor 466, winding o1" 0;

counting relay 460, left lower contact o fg sequence switch spring 411.. to groundedbab.

tery. The 0 counting relay-460 operatesin; the fundamental circuit traced to establlsh a locking circuit for itself and an operating circuit for the 0 counting, relay.

This operating-circuit iseffective upon the upwardmovement of the-test selector switch elevator when brush 710 is engaged with. anon-conducting portion of commutator segment 706, thus removing the shunt ground from the 0 counting relay 461. ating circuit and locking circuit may be traced from ground through the armature and contact of the O counting relay 460, winding of 0 counting relay461, windingot- 0 counting relay 460 to grounded battery through the left lower contact of sequence switch spring 411. 1 r

The operation of the 0 counting relay 461 opens the energizing circuit for updrive magnet 702, thus arresting the upward movement of the test selector switch ele- 'vator. It will be noted thatthezero bank. The operation of the 0 counting relay-461 further' establishes a circuit to rotate the sea quence switch Fig; 4 from;position;4.to;po;Z sit-ion 5. This circuit may lie-traced; from ground throughthe armatureiand contact of- 0 counting relay 461, leftilowencontact of; sequence switch;springy401, winding of: sequence switch,magnet-400, to grounded-bat; ery Upon; he. r n. t: he: eq n e This operr the locking circuit for 0 and: 0- counting relays 460 and 461 is opened to cause-their release. The release of the countingrelays establishes a circuit to rotate the sequence switch Fig, 5'to position 6. This circuit maybe traced, from ground, through the normalarmature and contact 01 0 counting relay 461, left upper contact of sequence. switch spring 404, right outer contact and armatureof relay 428, lower contact of sequence switch spring 412, winding of sequence-switch1nagnet'400 to grounded'bats tery.

In position 6 of the sequence switch, Fig.- 4, circuits are established to directively control the test selector forgroup selection and to actuate trip magnet 703. The circuit for actuating trip magnet 703 may be. traced from grounded; battery, through the winding of magnet 703, conductor 726, conductor 226,, lower contact of sequenceswitch spring209, conductor 363 to-ground througl'rthe-left upper; contact or sequence; switch spring 409. Theactuation of trip magneti703positions the trip lOCldll-ibl'llfllP. ner. to; trip the brushes: ofthe zero bank uponi urther upward movement of the test selectorswitch elevator. The actuatingcin cuiti for updrive magnet 7 02 may. be traced" from grounded battery, through theiwind i ing of" magnet 702,' cond uctor 725, conduc-- tor 22 5,. lower contact of sequence" switch. spring; 208, conductor 364, upper-contact of sequence switch spring 412, right'ou ter armature and contact of relay 428, left upper contact 01' sequence switch spring; 404, to ground through the I normal contact and ar mature-of the 0 counting relay 461. The test selector switch elevator is now drivenv in anupward movement to associate brush 709 with the. segments of commutator 704.- Upon the engagement of: brush 70.9with the conducting portion of commutator segment 704, the fundamental circuit is established to operate thecounting relays. This circuit may be t-raced from ground through the lower; contact of sequence switch spring 740, brush 709,- commutator segment- 704, conductor T23, co'nductor 223, lower contact of sequence, switch spring 206, conductor 366, lower contacts; of sequence switch spring 408, right inner contacts of key 14, register brush 54 and. its associated contact, terminal strip 60, terminal. strip 61, conductor30, conductor 466, winding o'tO counting relay 460, to grounded battery through the left lower contact of sequence-switch spring 411.- The 0 countingrelay isoperated inthe-cir- 'cuit traced toyestabl-ish alockingl circuit for itself andv an operating circuit; for the 0" counting relay 4.61 which is eifective uponfurther upward movement of the testg selector switclnelevator, as; previously described. he p r gm r u tforthefl ounting e.-

la th aapreriousl lasticities The 0 counting relay in attracting its armature opens the energizing circuit for up drive nr gnet 'Z arresting the upwa d ZIlGVQDl it of the test selector switch elera tor. s T 31., 733 and T34 of the test selector switch are now engaged with the first set of terminals in the Zero group of the Zero bani: to which the final selector switch, Fig. 8 is associated.

The 0' counting relay in attracting its nurture, further establishes a circuit to ro tate the sequence switch, Fig. 4, from position 6 to position i. This circuit may be traced from ground, through the armatin'o and contact of the 0 counting relay, left outer contacts of lcey 14, upper contact of sequence-switch spring 402, winding of se quence switch magnet 400 to grounded battery.

In position 7, the final selector switch Fig. 8, is tested to ascertain whether it'is busy or 11; lo. A busy final selector is characterized hy ground connected to terminal Assuming that a busy final selector is encountered, circuit is establishedthrough the left winding of relay 426. This circuit may be traced from grounded battery, through the left winding of relay 426, contacts of key 441, left inner contacts of key 440, right contact and arn'iature of relay 426, left outer contacts of key 630, left normal contact and armature of relay 523, left normal contact and armature of relay 524, conductor 370, lower contact of sequence switch spring 217., conductor 231, conductor 731', brush 732, nal 735, to ground through the right upper contact of sequence switch spring 301 It will be notedthat the actuating circuit for relay 428 is opened upon the rotation of the sequence switch, Fig. 4, from position 6 to position 7, and upon the release of relay ''8, the eni-zrgizing circuit through the right nding of relay 426 is opened, but the cir cult established to a busy terminal selector, through the left winding of relay 426 maintains this relay in an operated position. During the period of time that relay 426 is nraintained operated from a circuit through its left winding; to a busy final selector, lamp 444 is lighted. The circuit for lighting lamp 444 may be traced from grounded battery, through resistance 445, lamp 444, right contact and armature of relay 426, to the ground characterizing the final selector as busy as previously traced. hen an idle "final selector is encountered by the test selectorand the sequence switch, Fig. 4, retates to position 7, a circuit is not established through the left winding of relay 426, and therefore it releases.

The release of relay 426 establishes a circuit to characterize the idle final selector circuit busy to other selector switches attempting to seize it for ser ice connect on. This circuit may be traced from ground,

through the right upper contact of sequence switch spring 410, right normal contact and armature of relay 426, and thence over the path previously traced to terminal 735. lt

will be remembered that rela 427 is maintained in an operated position. The release of relay 426 further establishes a circuit through the contact and armature of relay 427, to operate relay 431. This circuit may be traced from grounded battery, through the winding of relay 431, right outer contacts of key 440, left contact and armature of re lay 427, left normal contact and arniature of relay 426, brush 456, and its associated contact, to ground through the right normal armature and contact of relay 434.

The operation of relay 431 establishes circuit paths from the tip and ring conductor of the final selector circuit switch, Fig. 8, to the test and control circuit, Figs. 5 and 6. The tip and ring circuits will be traced upon the establishment of the fundamental circuit to directively control the final selector switch. Relay 431 in attracting its right outer armature, transfers the alarm circuit leads. This will be described in detail in connection with the compound alarm circuit shown in Fig. 9'. The operation of relay 431 further establishes a circuit to rotate the sequence switch shown in 6 from its normal position 1 to position 2. This circuit may be traced from grounded battery,

through the winding of sequence s witch mag.- net 600, right upper contact of sequence switch spring 608, lower contacts of sequence switch spring 504, to ground through the left inner contact and armature of relay 431.

A multi-test is now made of the operating functions of the final selector switch and its auxiliary circuits as outlined in the general description. To make this multi-test key 631 is actuated. With key 631 in its normal position only one of the plurality of tests is made. The test made depends upon the position of the sequence switch Fig. 5.

In position 2 of the sequence switch Fig. 6', a circuit is established to operate relay 518, Fig. 5, for a continuity test of the ring conductor of the final selector circuit Fig. 8. This-circuit may be traced from grounded battery, through the winding of relay 518, upper contact of sequenceswitch spring 505, left upper contact of sequence switch spring 616, right inner contact and armature of relay 431, conductor 369, low-er contact of sequence switch spring 218, conductor 230,0011- ductor 730, brush 733, terminal 736, conductor 851, resistance 826 to ground through the right upper contact of sequence switch spring 816. t

In position 2 of the sequence switch Fig. 6, the fundamental circuit is established to directively control the positioning of the final selector switch Fig. 8. This circuit may be traced from grounded battery,

.right upperv contact of sequence switch" ,of relay 822 establishes a through the left lower and upper contact of sequence switch spring 815 shown in F1 8, right wmdlng of relay 821., rlght lower contact of sequence switch spring 810, left lower contact. of sequence SWltCll'SPllIlg 808, conductor 850, terminal 737, brush 7351, conductor 729, conductor 229, lower contact of sequence switch spring 222, conductor 360, left upper contactand arn ature or relay 431, contact and armature of relay 518, lower contact of sequence switch spring 615, resistance' 629, resistance 628, normal contact and lower contact'of sequence switch spring 80%,

left contact and armature of relay 821, to ground through the right lower contact of sequence switch spring 811. The operation circuit to rotate the sequence switch Fig. 8 from position 1 to position 2. 'v This circuit may be traced from,

grounded-battery, through the winding of sequence switch magnet 800, right lower and upper contactsof sequence switch spring 803 to groundthrough the right contact and armature of relay 822. Upon the rotation of sequence switch Fig. 8 from position 1 to position 2, a circuit is established for relay 821. This circuit may be traced from grounded battery, through the left lo'we and upper contacts of sequence switch spring 815, right winding of relay 821, right upper and lower contacts of sequence switch spring 813, right contact and'armature of relay 821,

spring 810, left lower contact or sequence switch spring 808 and thence over the fun-v damental circuit to ground through the winding of the stepping relay (323 as previ ously traced. v 7

In position 2 of the sequence switch lfii 8, a further circuit is established to actuate the lu h speed updrive magnet 831. This circuit may be traced from grounded lattm'yi through the winding magnet 831, right upper and left lower contacts of sequence switch spring 808, left contact and armature of relay 821. to ground through the right lower contact of sequence switch spring 811.

The final'selector switch elevator is now driven upward to make final brush selection.

Upon the upward increment of the selector 84 1-, with the first conducting portion of wrestle commutator segment 841, establishes a shunt to release stepping relay 7 This shunt circuit may be traced from ground through the left upper contact of sequence switch spr1ng816, brush 84 i, conducting portion of stepping relay 623 and to maintain relay 821 in an operated position.

The initial. operation of stepping relay 623 shown in Fig. 6 establishes a circuitto operate counting relay 9. This circuit maybe traced from ground through the armature and contact of relay 6.23, lower contact of sequence switch spring 605, upper contact of sequence switch spring 621, normal armature and contact of counting relay 9', winding 'of counting relay 9, lower contact of se quence switch spring 610, togrounded battery. establishes a locking circuit for itself and an operating circuit for relay 9f which is effective upon the removal of the shunt by the release of the stepping relay 623.. Thiscircuit may be'tr'ace'd from grounded battery,

through the lower contact of sequence switch The operation of countin rela 9 the non-conducting portion of commutator I segment 841, next. above the first conducting portion of said commutator, the steppingre lay 823 is again energized to establish a cirt T r cu it IOI'VCOUHUHQ relay llo. This clrcult may be traced from ground through the armature and contact of stepping relay 623, lower contact of sequence sw tch spring 605, upper contact of sequence switch spring 621,

armature and contact of counting relay No. 9, normal armature and contact of counting re ay No. '8, winding of counting relay No. 8, lower contact of sequence switch spring 601, upper contact of sequence switch spring 610 to grounded battery. The operation of counting relay No. 8 establishes a locking circuit for itself and an operatingcircuit for counting relay No. 8 which s effective upon the release of stepping relay 623. The

release of relay 623 occurs upon the engage-'- ment of brush 8441; ith the conducting portion of commutator segment 841 next above the non-conducting portion of said segment. As the final selector switch elevator moves upward, the counting relays are operated in sequence as described for counting relays 9,"

shown in Fig. 8. The release oi relay opens the energizing circuit for the high speed updriye magnet S31, arresting the upward movement of the selector switch elevator. The release of relay 821 further establishes a circuit to rotate the sequence switch Fig. 8 from position 2 to pos' on s. This circuit may be traced from grounded battery, through the winding of sequence switch magnet 800, right lower contact sequence switch spring 807, left normal con tact and armature of relay 821 to ground through the right lower contact of set :euce switch spring 811. The sequence switch is arrested in this position until the fundamental circuit is again established.

The operation of counting relay BO establishes a circuit to rotate the sequence switch shown in Fig. 6 from position 2 to position 3. This circuit may be traced from,

grounded battery, through the winding of sequence switch 1 7 net (300, right lower (ontaet of sequence so .teh spring 608, to ground through the contact and armature of the B0 sequence switch, Fig. 6, from. position 2 to position 3, opens the loclr' circuit for the counting relays t0 cause tne release. The release of counting relay es ablishes a. ('ircuit to rotate the sequence switch, Fig. 6, from position 3 to position/l. This circuit may be traced from grounded battery, through the wi d ng of sequence switch ma 'net 600, lett'lower contact of sequence switch spring 6(308 to ground through the normal contact and armature of the 18G counting relay.

in position 4 of the sequence switch, Fig. 6, the fundamental circuit is again estahlished lor final tens selection as previously traced to operate the stepping relay 623 and relay 821 of Fig. 8. The operation of stepping relay 623 establishes a circuit to operate the No. 9 counting relay. This circuit may be traced from ground through the arn'iature and contact of stepping relay 623, lower contact of sequence switch spring 25, right lower contact of sequence switch spring 621, normal contact andarmature of the No. 9*counting relay, winding of the No. 9 counting relay to grounded battery, through the lower contact of sequence switch spring 610. This actuating circuit remains estahlishedyuntil a shunt circuit is established for stepping relay 623 by the upward movement of the final selector switch elevator.

In positions 3 to 5 of the sequence switch shown in Fig. 8, an obvious energizing circuit is established for trip magnet 833 to rotate the tripping spindle to tripbrushes 853, 854i and 855 upon further upward more ment of the final selector switch elevator.

The operation of relay 89.1 establishes a rircuit to rotate the sequence switch, Fig.

sure oi 'rclay 821 to ground through the right lower contact of sequence switch spring 811. The sequence switch Fig. 8 in rotating from position to position 4% establishes a locking circuit for relay 821 as previously traced. ln position 4, a circuit is again established to ei'iergize the high speed upe magnet 881. This circuit may be traced from grounded battery, through the winding of magnet 831, right upper and left lower eontz-icts 0r sequence switch spring 808, lots contact and armature of relay 821, to ground through the right lower contact of sequence switch spring 811. Upon the upward movement oi the selector switch eleish 8&8 is engaged with the conto; portion of commutator segment 8 1-0 )llSll a shunt to release stepping relay .lhis shunt circuit may be traced from ground through the left upper contact of switch spring 816, brush 84S, commutator 84.0, left upper contact of sequence switch spr g 810, left lower contact of sequence switch spring 808 where a junction is estahli l with the fundamental circuit.

Upoa the initialrclease of stepping relay an operating circuit is etiective for tl e c t e lecor switch elevator, m'ush 8&3 is disen- "ed from the conducting portion of the con'nnutator segment 8&0 and engaged with a nononducting portion, causing the step ping relay to again operate. The op.-

, relay, the fundamental circuit is opened to release relay 821. The release of relay 821 opens the energizing circuit for high speed .updriye magnet 831 arresting the upwz rd movement of the selector switch elevator; The release of relay 821 further establishes a circuit to rotate the sequence switch Fig. 8 from position 4 to position 5. This circuit may be traced from grounded battery,

loo 

